This invention relates to pattern scanners and is particularly applicable to lay planning machines.
A lay planning machine is a machine for use in the garment trade for planning lays from graded patterns and for producing markers, i.e. printed sheets conveying a planned arrangement of the pattern from which garment pieces may be cut.
Software is available for lay planning, but it requires that the user have a computer with suitable peripherals, in particular an input device, such as a digitizer, for reading the patterns.
A conventional input device available in the art comprises a stylus connected to a stylus position sensing means and a memory means, whereby said stylus is manually traced around the boundary of a pattern piece thereby providing a memory map of the external boundary of the pattern piece. This device, however, requires a skilled operator to trace the pattern piece boundary accurately. British Specification Nos. 1162096 and 1165223 disclose devices which detect a pattern curve boundary and trace around the boundary automatically to enable one to provide a memory map of the boundary.
These devices necessarily take a considerable amount of time in mapping the boundary as continual calculation is involved during the boundary tracing, as are a large number of direction changes over each section of a boundary.
It is thus desirable to maintain the objective of automatic scanning of a pattern piece whilst at the same time simplifying the scanner functioning, in particular simplifying the mechanical functioning of the scanner.